Talk:Calorie restriction

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Unknown, unknown, unknown[edit]

Hi DocJames and Zefr. Can you please explain why this article needs to have three statements that the longterm effects of moderate CR on humans is unknown? DocJames writes in his edit summary that he is restoring "The most important part of the article." Perhaps we share a fear for life of a person with low BMI who might read something that might encourage them to restrict calories. Speaking as a new member of Wikiproject:Medicine, I am sorry but the net effect of three statements is that this article is biased against the idea of caloric restriction in humans. -SusanLesch (talk) 20:58, 7 November 2017 (UTC)

You said: "... three statements that the longterm effects of moderate CR on humans is unknown?" Could you specify those 3 statements? Edited the section on human research, and rearranged the content for a more logical order. See what you think. --Zefr (talk) 00:17, 8 November 2017 (UTC)
@Zefr: The 3 statements (before your edits):
  • "In humans, the long-term health effects of moderate caloric restriction with sufficient nutrients are unknown." (in the lead)
  • "In humans, the long-term health effects of moderate caloric restriction with sufficient nutrients are unknown." (the first sentence after the lead)
  • "Studies have been conducted to examine the effects of calorie restriction with adequate intake of nutrients in humans; however, long-term effects are unknown." (under Research > Humans)
It will take me a day or so to read your sources. -SusanLesch (talk) 01:46, 8 November 2017 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────@DocJames: I am waiting for your reply. -SusanLesch (talk) 15:27, 8 November 2017 (UTC)

A space will be needed between "Doc" and "James" for the ping to work. The lead is supposed to repeat the body of the text. I do not see it as undue. Doc James (talk · contribs · email) 12:41, 9 November 2017 (UTC)
The third mention should probably be reworded atleast "however, long-term effects are unknown" should be more like "long-term studies have not been done" as it is in the research section, not the health effects section. Galobtter (talk) 13:59, 9 November 2017 (UTC)
Aha, thank you for the correction on spelling, Doc James. You haven't answered my question though. (I still owe Zefr my take on your sourcing for the section Research > Humans.) Why is this article biased against calorie restriction? You keep saying, over and over, that the effect of longterm moderate CR on humans is unknown. Yet you selectively cite sources that say CR can be beneficial to omit that fact. And you selectively admit primary material that supports your view and remove primary material to the contrary. I doubt this is intentional but this article needs work. -SusanLesch (talk) 16:45, 9 November 2017 (UTC)
It is normal to be skeptical. It is up to those proposing the claim to present the research not the other way around. And extra ordinary claims require extra ordinarily good sources. Doc James (talk · contribs · email) 07:42, 10 November 2017 (UTC)
@Doc James: You cite the Minnesota Starvation Experiment but you give page 1113 for every instance (the citation is reused for a total of four citations). What are the correct citations and why for the love of Pete don't you use them? I tried to follow one in particular, under "Biomarkers for cardiovascular risk," where you say, "Similar effects were also seen during a "natural experiment" in Biosphere 2,[81] and in subjects in the “Minnesota Starvation Experiment” during World War II." I was disappointed to find the actual Appendix cited is about Methods. Also, this is a primary source. Thus my criticism above that you remove and include primary material selectively. May I suggest They Starved So That Others Be Better Fed: Remembering Ancel Keys and the Minnesota Experiment or some other secondary source? -SusanLesch (talk) 22:01, 10 November 2017 (UTC)
Under Health effects, you say, "The authors of a 2007 review of the caloric restriction literature warned that "[i]t is possible that even moderate calorie restriction may be harmful in specific patient populations, such as lean persons who have minimal amounts of body fat."
In their paper, Fontana and Klien say under conclusions, "Calorie restriction in adult men and women causes beneficial meta- bolic, hormonal, and functional changes, but the precise amount of calorie intake or body fat mass associated with optimal health and maximum longevity in humans is not known. In addition, it is possible that even moderate calorie restriction may be harmful in specific patient populations, such as lean persons who have minimal amounts of body fat."
This is the instance where I find you guys selectively quoting somebody who thinks CR is a good thing but omitting that fact. My problem now is that Zefr will not accept a more recent updated review by Fontana, "Calorie restriction in humans: An update" (2017) (he thinks it is "low quality"). So please at least rewrite this to reflect the man's real words. -SusanLesch (talk) 22:22, 10 November 2017 (UTC)
When one editor doubts the interpretation of WP:MEDRS by another, that first editor can 1) make a revision and cite the source, Most et al. to see if it stands, or 2) take the issue to a discussion board, either WT:MED or WT:MEDRS, where other editors will chime in. My response here was only my interpretation that the quality for human evidence in the Most review was inadequate to include. --Zefr (talk) 23:49, 10 November 2017 (UTC)
Hi @Zefr: Maybe you would do me a favor. The following list comes from Das et al. 2017 ("Nutrition modulation of human aging: The calorie restriction paradigm") which I am careful not to add to the article. Can you say if each one of the five is a true statement or is false?
SusanLesch: responses below following each point, although I don't have access to the full Das article, so will be brief. --Zefr (talk) 16:32, 12 November 2017 (UTC)
  • CR's primary aim is: "attenuating or delaying the onset of physiological and metabolic effects of aging and associated disabilities." (p. 148)
False. Keeping it simple, the initial goal and effect of CR are on weight loss, the numerous mechanisms of which I sense are the more interesting and scientifically challenging events to define, before anti-aging mechanisms are addressed.
  • "Additionally, it is unknown whether different CR regimes, such as alternate day fasting (ADF), intermittent fasting (IF) or time restricted feeding (TRF) have differing effects on healthspan or lifespan (Patterson et al., 2015)." (p. 150)
True. There is insufficient human research to discern such effects.
  • CALERIE-2 (2015) found no reduction in core body temp or in resting metabolic rate
True and false, respectively. In the CALERIE study published here, Table 1 and 5th paragraph of the Discussion, the authors report no effect on body temperature, and a significant decrease in resting metabolic rate only in the first year.
  • T3 levels determine basal metabolic rate (p. 154)
Partly true. T3 has numerous physiological roles (explained in its WP article), including an effect on metabolic rate.
  • CR reduces T3 and IGF1 activity, and increases cortisol and adiponectin levels (p. 154, and other markers that page; I stopped at the word "controversial.")
True for T3. According to the CALERIE article, CR reduced T3 by 16% in the first year and 22% in the 2nd year. I saw no results there for the other biomarkers.
Thank you. I don't have the necessary credentials to know one way or the other but these seemed like solid pieces of information. -SusanLesch (talk) 00:20, 12 November 2017 (UTC)
The measurements you've highlighted with these questions are biomarkers for changes resulting from CR, but there is insufficient knowledge about their precise roles, alone or integrated, for reducing body weight and extending life. The Das study and CALERIE (concluded in 2013) were works in progress, so would be defined as inconclusive primary research, and likely not usable in the article. As indicated by Doc James below, the article is rated as a C class and needs more and better sources, which are not available currently. As I feel we have discussed this enough, I am moving on to other editing and don't wish to be involved in further details here. --Zefr (talk) 16:32, 12 November 2017 (UTC)

Where do I cite the "Minnesota Starvation Experiment"? Doc James (talk · contribs · email) 06:00, 11 November 2017 (UTC)

@Doc James: Sorry my use of you refers to the group of people who answer questions here and who edit the article. One might say you are stewards (WP:STEWARDSHIP). In the English language the word is both singular and plural so I should have rephrased. I use you apart from "we" because I can't endorse this article as written. The search function in your browser is a good way to find the citations. -SusanLesch (talk) 16:12, 11 November 2017 (UTC)
Who says I endorse it as written either? It is less bad than it once was, but it is a C class for a reason. Doc James (talk · contribs · email) 09:21, 12 November 2017 (UTC)
Thank you, disapproval noted, Doc James. Let's address the four or five things given here that would help. I'm going to work on the History section which currently stretches a Fontana paper out of recognition. -SusanLesch (talk) 14:54, 12 November 2017 (UTC)

Research sources[edit]

Hi Zefr. I have trouble with the section on Humans under Research. Three sentences with three references that have been cited a sum total of 148 times. Can we agree to throw out Everitt and Le Couter? Their paper seems to be written as an introduction and reads much like a high school report. My objection is that they belittle years of life, "it is estimated that long-term CR to prevent excessive weight gain could add only 3–13 years to life expectancy." A drug that could add that much to a cancer patient's life would be a bestseller. And according to them the Okinawans used to live "only" 4 years longer. A small empire was founded on those same 4 years. I think that last sentence is repetitive. Why not just omit the whole thing? We ought to build up the sources for these statements instead of diluting the message. -SusanLesch (talk) 17:50, 9 November 2017 (UTC)

The 3 sentences seem reasonably accurate and worthwhile to state, but in a search for better sources, it becomes obvious that CR is difficult, if not impossible, to study and quantify for health or longevity benefits. Without absolute control of subjects, similarly frustrated as in feeding and nutrition clinical trials, CR must be a challenging condition to control, hence the absence of high-quality, large-scale clinical research and comprehensive systematic reviews on human results. The 3 references used are also > 7 years out of date, and therefore inadequate for the encyclopedia. --Zefr (talk) 18:12, 9 November 2017 (UTC)
May I suggest this reference? Calorie restriction in humans: An update (2017). May I ask why this article doesn't link to CALERIE? Why doesn't it mention Human Vitality and Efficiency Under Prolonged Restricted Diet (Benedict et al. 1919)? Internet archive has a free copy. The Gale Encyclopedia of Diets (editor is Kristen Key, 2nd edition, copyright 2013) has an article on calorie restriction. I'm still digging. -SusanLesch (talk) 22:48, 9 November 2017 (UTC)
Thanks, but I think all these sources would be categorized as "low-quality" and unusable under WP:MEDASSESS. --Zefr (talk) 23:03, 9 November 2017 (UTC)
There's a tertiary source and a systematic review (granted not reviewing randomized controlled trials). A link to CALERIE and a mention of the first major study are both intended to make this encyclopedia more complete (neither is a source). It is questionable why they aren't here already. But you choose not to answer that. -SusanLesch (talk) 23:45, 9 November 2017 (UTC)

Confilict of interest[edit]

I need to declare a possible conflict: the first author of this review is one of my teachers plus I enrolled in her class for next semester. Because she isn't teaching us this subject, while I knew she was among the authors of the 2015 study, I did not know she had written the review that is possibly a very good source. After looking into COI, evidently this might not be a problem. This is a first for me. Apologies for taking so long to declare. -SusanLesch (talk) 22:46, 9 November 2017 (UTC)

No worries. Thanks for being open about this. Doc James (talk · contribs · email) 07:41, 10 November 2017 (UTC)

Subject and objective[edit]

One problem with this article is that the subject of all these experiments switches from humans to animals and back and forth again. A second problem is that the objective of CR seems to sway in the wind. Some places, CR is intended to prolong life, and in others CR reduces risk factors for disease, and in others CR is a weight loss tactic. Do you think this is a fair assessment and do you think the article can be improved? -SusanLesch (talk) 19:09, 10 November 2017 (UTC)

1 Health effects humans
   1.1 Risks of malnutrition
2 Mechanisms mice, humans, rodents, yeast
   2.1 Temperature 
   2.2 Hormesis
   2.3 Evolution
   2.4 Chromatin and PHA-4
   2.5 Reduced DNA damage
   2.6 Sirtuin-mediated mechanism
3 Caloric restriction mimetics humans, yeast, worms, flies, fish, mice
   3.1 Sirtuins
4 History one human generalized to other species
5 Research humans, primates and humans, rodents, yeast (pretty good!)
   5.1 Humans
   5.2 Primates
   5.3 Rodents
   5.4 Yeast
6 Effects rodents, monkeys, monkeys, animals, animals
   6.1 Activity levels
   6.2 Stereotyped behavior
   6.3 Aggression
   6.4 Obese controls

To this I would add that two sentences are gibberish. Under Mechanisms, "the mechanism by which caloric restriction works is still not well understood". I don't believe anything can "work" unless we know its objective. Second, I changed the second sentence in the lead, ""Low" can be defined relative to the subject's previous intake before intentionally restricting calories, or relative to an average person of similar body type." to "Reduce" can be defined.... Either way, we would need to specify what [something] is "relative to an average person of similar body type." -SusanLesch (talk) 21:43, 10 November 2017 (UTC)

We generally keep headings short. I do not see this extension as an improvement. Yes the mechanisms are proposed ones. We do not even know if CR really has the benefits claimed. Doc James (talk · contribs · email) 05:45, 11 November 2017 (UTC)
@Doc James: I'm not sure you understand what the TOC above signifies. It is a summary, top to bottom, of the topics in this article as they switch from humans to other animals and then back and forth. It's not a proposed extension of the headings in the article. My questions for you are above the TOC. Now you've raised another question though. This article will need to admit more recent sources, some of which will state positive things about CR. I don't believe the selective quotation of Fontana 2007 speaks very well for Wikipedia. -SusanLesch (talk) 00:30, 12 November 2017 (UTC)